“…Typically, the concentration of platelets in PRP is about three to six times the normal platelet concentration in peripheral blood [27,28], and can therefore generate an elevated concentration of growth factors [11,27,29]. This supraphysiological factor concentration in PRP is achieved through platelet activation, degranulation and release of their stored growth factors [11,[29][30][31], e.g., VEGF (vascular endothelial growth factor), PDGF (platelet-derived growth factor), EGF (epidermal growth factor), IGF-1 (insulin-like growth factor-1), bFGF (basic fibroblast growth factor), TGF-beta1 (transforming growth factor beta-1), TSP-1 (thrombospondin-1) and PF-4 (platelet factor-4) [23,[31][32][33][34][35]. Evidently, PRP is a composite mixture of both angiogenesis-promoting (e.g., VEGF, PDGF) and angiogenesis-inhibiting (e.g., TSP-1, PF-4) protein factors, which makes the analysis of this secretome's net angiogenic effect(s) inherently complex.…”